JEE Main 2026 — Chemistry Physical Chemistry

2026mcqmedium

Given at $298$ K: $E^{\ominus}_{Fe^{2+}/Fe} = X$ Volt; $E^{\ominus}_{Fe^{3+}/Fe} = Y$ Volt. The $E^{\ominus}_{Fe^{3+}/Fe^{2+}}$ in Volt at $298$ K is given by:

Official previous-year question

Held on 8 Apr 2026 · Verified 6 Jul 2026.

Options

A
$2X-3Y$
B
$3Y-2X$
C
$3Y+2X$
D
$Y+X$

Did you get this right?

Solution

The half-reactions and their standard Gibbs free energy changes are given by:

$Fe^{2+} + 2e^{-} \rightarrow Fe$

$\Delta G^{\ominus}_{1} = -2FX$

$Fe^{3+} + 3e^{-} \rightarrow Fe$

$\Delta G^{\ominus}_{2} = -3FY$

The required half-reaction is:

$Fe^{3+} + e^{-} \rightarrow Fe^{2+}$

$\Delta G^{\ominus}_{3} = -1FE^{\ominus}_{Fe^{3+}/Fe^{2+}}$

This reaction is obtained by subtracting the first reaction from the second reaction:

$\Delta G^{\ominus}_{3} = \Delta G^{\ominus}_{2} - \Delta G^{\ominus}_{1}$

$-FE^{\ominus}_{Fe^{3+}/Fe^{2+}} = -3FY - (-2FX)$

$-FE^{\ominus}_{Fe^{3+}/Fe^{2+}} = -3FY + 2FX$

$E^{\ominus}_{Fe^{3+}/Fe^{2+}} = 3Y - 2X$

Answer: $3Y-2X$

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JEE Main 2026 — Chemistry Physical Chemistry

2026mcqmedium

Given at $298$ K: $E^{\ominus}_{Fe^{2+}/Fe} = X$ Volt; $E^{\ominus}_{Fe^{3+}/Fe} = Y$ Volt. The $E^{\ominus}_{Fe^{3+}/Fe^{2+}}$ in Volt at $298$ K is given by:

Official previous-year question

Held on 8 Apr 2026 · Verified 6 Jul 2026.

Options

A
$2X-3Y$
B
$3Y-2X$
C
$3Y+2X$
D
$Y+X$

Did you get this right?

Solution

The half-reactions and their standard Gibbs free energy changes are given by:

$Fe^{2+} + 2e^{-} \rightarrow Fe$

$\Delta G^{\ominus}_{1} = -2FX$

$Fe^{3+} + 3e^{-} \rightarrow Fe$

$\Delta G^{\ominus}_{2} = -3FY$

The required half-reaction is:

$Fe^{3+} + e^{-} \rightarrow Fe^{2+}$

$\Delta G^{\ominus}_{3} = -1FE^{\ominus}_{Fe^{3+}/Fe^{2+}}$

This reaction is obtained by subtracting the first reaction from the second reaction:

$\Delta G^{\ominus}_{3} = \Delta G^{\ominus}_{2} - \Delta G^{\ominus}_{1}$

$-FE^{\ominus}_{Fe^{3+}/Fe^{2+}} = -3FY - (-2FX)$

$-FE^{\ominus}_{Fe^{3+}/Fe^{2+}} = -3FY + 2FX$

$E^{\ominus}_{Fe^{3+}/Fe^{2+}} = 3Y - 2X$

Answer: $3Y-2X$

Your note

JEE Main Physical Chemistry in other years

Keep practicing Physical Chemistry

Work through every JEE Main Physical Chemistry PYQ, year by year.

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JEE Main 2026 — Chemistry Physical Chemistry

Options

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

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JEE Main 2026 — Chemistry Physical Chemistry

Options

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry